The environmental factors (pollutants such as ozone and polycyclic aromatic hydrocarbons, oxygen, solar UV radiation) can affect the major structural protein collagen. These environmental effects on collagen will be investigated. 1) The pH and wavelength dependent of photoreaction rate is determined from the UV-induced fluorescence/absorption changes of fluorescent chromophores in skin, cornea and tail tendon collagens and compared with that of both the fluorescent crosslink pyridinoline in the hard tissue collagens and the model compound 3-hydroxy-N-methyl-pyridinium ion. The formation of transient intermediates is sought to elucidate the mechanism of these photoreactions. The possible photolytic dissociation of fluorescent crosslinks is studied by gel-filtration and gel-electrophoresis. With pyridinoline collagens, the dissociation of one chain with hydroxy-lysine from double-chained glutaconic aldehyde can be expected with the formation of new amino and carbonyl groups. Ozonolysis of the latter chains may possibly cause further splitting of the two chains. 2) The ozone-sensitive retardation of collagen fibril formation is investigated by the effect of ozone upon aldehyde reactivity, aldol crosslinks and aggregates, and new crosslinking. 3) Studies on hydrocarbon-collagen interactions are focused on the isolation of covalently-bonded benz(a)anthracene/benzo(a)pyrene - type I/type III collagen chains and their trypsin-treatment to verify the covalent nature. 4) Continued efforts to elucidate the relationship between fluorescent chromophores and oxidized collagen in soft tissues are the long-term objectives.